Rooms with wall to wall, or built in bookcases are prime candidates for editing or removing altogether if possible. Don't get me wrong, we hold no personal grudge against the written word, rather it's the weight they can create in a room when assembled en masse. Much of what we do as professional home stagers is create additional visual space in each room. Our general recommendation is to remove at least 1/3 of the books if the bookcases remain in the room. Do take care to remove any political, religious or controversial titles as a rule. I realize that those of you who are voracious readers and book collectors will be horrified or at least slightly offended to read this. To make you feel better, in this age of e-readers, Kindle's and book apps, I may be one of the few home owners actually adding a library in lieu of a living room. (Note: I'm also not selling my house). I personally delight in the feel of a book and the promise that the pages hold. For me, reading and appreciating a good book is a tactile experience that even the best well-lit Kindle device cannot offer. As for staging, although we typically recommend removing books in their overflowing state, books are a wonderful tool to backfill areas where overly personal items may have been placed. They can lightly fill built-in shelves, as well as add interest and speak to the demographic of the buyer. For example, we always add a golf book when staging in the communities of Creighton Farms, Belmont Country Club and River Creek, placed on the coffee table in a prominent arrangement. Professional home stagers never adhere heavily to a theme of any sort, however our goal is to let the staging speak to the mindset of the type of person that would choose that home. Books help to convey that sentiment. Another example is adding books on Virginia Hunt Country when staging in such locales as Delaplane, Middleburg and Western Loudoun. The photos illustrate some of our favorite ways we incorporate books as accessories and decor, not just for staging but for interior redesign as well. We often use stacks of books that provide height, color and texture on large coffee tables.
We have even used a book to create symmetrical height when staging occupied homes. Placing a book under a table lamp evens out mismatched side tables or nightstands. 
We even take it a step further and create a monochromatic look for bookshelves by painting books white for a more contemporary look. 
Removing the spines of worn hardback books and wrapping the stack in burlap ribbon provides texture and interest for coastal spaces. 
We even found a way to utilize the lowly paperback by wrapping the cover over the book and tying the stacks with jute twine. The morale of the story is that for books and bookshelves, be creative, but less is more.The End